Numerous mechanical and metallurgical schemes have been employed in an attempt to reliably mate two circuit carrying substrates to provide an electrical interconnection there between. For example, pins on one substrate have been configured to plug into receptacles on a second substrate. The use of pins and plugs requires additional parts that increase the overall height of the assembly to the point where this technique is undesirable for use in devices that require very high density packaging.
Also, compliant metal springs or conductive elastomers are known to be inserted between the two substrates, the assembly being held together with clips or bands. Conductive elastomer interconnections reduce the height of the assembly, but require additional holding devices to provide the constant force required to insure deformation and conductivity of the elastomer. In addition, elastomer interconnections generally are relatively high resistance and not suitable for applications requiring low resistance connections, such as analog circuitry.
lastly, a metallurgical solder joint is most commonly formed between the two substrates using techniques known to those skilled in the art. Soldering provides a low profile, low resistance interconnection, however, the interconnection is not amenable to repeated disconnections. A soldered interconnection is often difficult to remove without damaging the accompanying substrates. In circuits fabricated from more advanced engineering thermoplastics, the soldering operation can deform or damage the underlying substrate, destroying the entire assembly. The connection formed by conventional soldering methods is also quite rigid, and can lead to significant mechanical stresses in the substrates after joining. In cases where a large areas of the substrate is to be joined to another substrate, such as in power transistors, ground planes, or shielding applications, effecting the solder joint can be quite difficult, requiring a skilled artisan. In these cases, the assembly of circuits and electrical interconnections must be performed manually, and leads to higher cost and lower quality than if performed by machines in an automated production environment.
Iin other applications, a conductive shield may be required to be configured about a circuit. However, the metal may not be amenable to soldering or welding. Such is the case in shielding applications where the interior of a shield is coated with nickel or other metal to provide shielding for devices capable of emanating electromagnetic radiation. These metal surfaces are not typically solderable, and the interconnection must be made by mechanical means. The connection cannot be welded however, because the heat produced during welding will deform the plastic housing.
When it is desired to shield sensitive portions of electrical circuits, a metal enclosure is typically placed over the affected portions of the circuit, and soldered to the circuit carrying substrate. For certain applications, the soldering operation must be precisely performed to insure that no large openings remain that will permit unwanted electromagnetic radiation to pass. Because of the uncontrollable nature of the soldering operation, it is difficult to insure that the enclosure has been reliably soldered. Clearly, an improved method of providing a uniform electrical seal is needed.